HF2014 Workshop, Beijing, China October 9 th -12 th, 2014 Constraints on FCC-ee lattice design Bastian Haerer ([email protected]) Constraints on the

HF2014 Workshop, Beijing, ChinaOctober 9th-12th, 2014

Constraints on FCC-ee lattice designBastian Haerer ([email protected]) 1

Constraints on the FCC-ee lattice from the compatibility with the FCC hadron collider

Bastian Haerer (CERN, Geneva; KIT, Karlsruhe), Wolfgang Bartmann, Bernhard Johannes Holzer, Daniel Schulte, Rogelio Tomas, Jorg Wenninger, Frank Zimmermann (CERN, Geneva), Michael James Syphers (MSU, East Lanning, Michigan), Ulrich Wienands (SLAC, Menlo Park, California)



Future Circular Collider Study



Future Circular Collider Study

Consists of three sub-studies:

• FCC-hh: 100 TeV proton collider• FCC-ee: 350 GeV lepton collider• FCC-he: electron-proton option

Every study has its own requirements, but technology for FCC-hh is most challenging!



Constraints on FCC-hh

• Magnet technology (Nb3Sn)

• Shape (racetrack vs. circle)• Geology• Overlap with LHC (if used as injector)• Injection, beam dump, experiments

Not covered today:• Constraints from hosting FCC-hh and FCC-ee in

the tunnel at the same time• Constraints from FCC-he



1) Bending radius

Proton beam energy: 50 TeV

Beam rigidity: Bρ = p/e ≈ 1.67×105 Tm

B = 20 T: ρ = 8.5 km

B = 16 T: ρ = 10.7 km

B = 16 T achievable with Nb3Sn technology!



2) Circumference

• Approx. 67% of circumference C are bends:

B = 20 T, ρ = 8.5 km C = 80 km

B = 16 T, ρ = 10.7 km C = 100 km

• RF frequency should be a multiple of RF frequency of LHC (bunch to bucket transfer)

C = 3×26.7 km = 80.1 km

C = 4×26.7 km = 106.8 km



3) Layout objectivesHadron machine• Max. momentum

limited by

High fill factor

As few straight sections as possible

Lepton machine• Limited by synchrotron

radiation power

High fill factor

High bending radius

Many straight sections for RF to limit sawtooth effect



FCC-ee: Sawtooth effect

12 RF sections 4 RF sections

Energy loss per turn (175 GeV beam energy): U0 = 7.7 GeV (4.3 %)



4) Shape

Circular shape (like LHC)• Preferred for lepton collider• Less resonances due to superperiodicity

Racetrack (like SSC)• Most of the infrastructure can be

concentrated at two main sites• Chromaticity correction easier A



5) Geology

Boundary Limits:• East: Pre-Alps• South: Rhone,

Vuache Mountain• West: Jura • North:

Lake Geneva

Courtesy: John Osborne



Lake Geneva

• The lake gets deeper to the North• The molasse rockhead as well

The tunnel level must be deeper in the earth

Riverbed

Molasse Rockhead

370

320

210

mASL




80 km circle

Courtesy: John Osborne, Yung Loo



100 km circle




Tilting the tunnel• LEP/LHC: 1.42 %

Maximize tunnel extend in molasse, minimize tunnel extend in limestone and moraines

Minimize shaft depths

P3P1 P7

(450m)(359m)(350m)


Limestone



100 km circle with tilt




6) Location relative to LHC

Required distance L for transfer lines depends on:

• Difference in depth d• Magnet technology

Courtesy: W. Bartmann

LHC

FCCd

L

• Beam energy• Max. slope of tunnel 5%

FCC and LHC should overlap, if LHC is used as injector



Distance for transfer lines

• Required length: L = 500 – 1500 m

3.9 T Tevatron dipoles

2.6 T CF JPARC magnets

1.8 T TI 2/8 dipoles

Beam energy: 3.5 TeVFilling factor: 0.75

8.3 T LHC dipoles

Courtesy: Wolfgang Bartmann

d

L



7) Length of Long Straight Sections

Space for septum, kicker magnet and absorbers for machine protection

Injection: Energy: 3.3 TeV• 600 m

Beam dump: Energy: 50 TeV• 800 m – 1000 m (?)



8) Experiments



Experiments FCC-hhInteraction region (IR) design for • Huge Detectors

L* = 46 m !!!• Length of single IR: ≈ 1200 m

• Head-on collision scheme

Court. R. Alemany, B. Holzer

β (m)



Experiments FCC-eeCompletely different IR design:

• Crossing angle• βy = 1 mm, L* = 2 m !!!

• Local chromaticity correction scheme

• IR length: ≈ 1600 m

More about IR design:

Roman Martin’s presentation

Court. R. Martin



Current FCC-ee design

Circular shape,

100 km circumference• 12 straight sections

Length: 1.5 km• 4 experiments• Length of arcs: 6.8 km

ρ ≈ 10.6 km

RF

RF RF

RF

RF

RFRF

RF

RF

RF

RF RF

IP

IP

IPIP

Details of the FCC-ee lattice were presented in my other talk



Resume

• Magnet technology sets constraints on bending radius and circumference

• Compromise for the layout must be found

• Injection, beam dump and experiments define length of the straight sections

• Geology and transfer lines define location of FCC



Thank you for your attention!Court. J. Wenninger





Unequally distributed RF



FCC-he design parameters



LHeC: IR layout

• A similar interaction scheme needs to be designed for FCC-he

Courtesy Max Klein



Experiments

Documents

HF2014 Workshop, Beijing, China October 9 th -12 th, 2014 Constraints on FCC-ee lattice design Bastian Haerer ([email protected]) Constraints on the